ALL CIE BIOLOGY DOUBTS HERE !!!

[Vampire-Love4ever]

An action spectrum is a graph showing the effectiveness of different wavelengths of light in stimulating the process being investigated. An absorption spectrum is a graph of the relative amounts of lights absorbed at different wavelengths by a pigment.

An action spectrum for photosynthesis is shown together with an absorption spectrum for the combined photosynthetic pigments.

http://5e.plantphys.net/images/ch07/wt0701c.png

NOte the close similarity, which indicates that the pigments, cholorophylls in particular, are those responsible for absorption of light in photosynthesis.

Thanks for your help.

[NidZ- Hero]

Explain why sickle cell anaemia is common in areas where malaria is endemic ?
0/n 6b p2
 

[**RoRo**]

Like MK said, Cu+ ions are not the shape of the sucrose so they do not attach themselves in the active-sites of the enzymes but elsewhere in the enzyme molecule. They alter the shape of the enzyme in such a way that the active site can no longer accomodate the substrate. As the substrate & inhibitor molecules attach on different parts of the enzyme, they are not competing for the same sites (non-competivite). Also, metal ions break the disulphide bonds(that help maintain the shape of the enzyme molecule). This causes the enzyme molecule's structure to be irreversibly altered.

Attach the questions please. 

What I meant is how would you know the shape of Cu ions, like why can't you say that it competes with the substrate and it becomes a competitive inhibitor?

I don't have a soft copy of the paper, so I'll type the questions for you in a while, or probably scan it for you.

Thanks Amelia and Master_Key

[**RoRo**]

I've attached the paper here in 2 parts.

[Sue T]

Biology Paper 5, specimen paper:
Q2. How to measure the curvature???

ok so as promised, Vampire-love - here r th answers 2 ur previous posts
first for ths one u dont really need 2 bother about that - there are lots of other points you could write - but anyways you can always say to use a protractor to measure th curvature - just state it like that u dont need to include so much detail 

1bi and ii) the marking scheme is messed up - they can always  be rong u no!
here is wat u shod get: mean for tissue A = 56  s_A= 2.357 and S_M= 0.75
mean for B = 123.3 s_B=2.312  and S_M= 0.73
the bar chart will become hard 2 draw with its error bars once you get these values - but dont worry its their fault :p its just a specimen paper...
thats it - good luck 2moro cya!

[Vampire-Love4ever]

ok so as promised, Vampire-love - here r th answers 2 ur previous posts
first for ths one u dont really need 2 bother about that - there are lots of other points you could write - but anyways you can always say to use a protractor to measure th curvature - just state it like that u dont need to include so much detail 

1bi and ii) the marking scheme is messed up - they can always  be rong u no!
here is wat u shod get: mean for tissue A = 56  s_A= 2.357 and S_M= 0.75
mean for B = 123.3 s_B=2.312  and S_M= 0.73
the bar chart will become hard 2 draw with its error bars once you get these values - but dont worry its their fault :p its just a specimen paper...
thats it - good luck 2moro cya!

Thank you my dear! ! ! See you after 8 hours!

[Vampire-Love4ever]

Any risk assessed by using hydrogen carbonate solutions?

[Amelia]

What I meant is how would you know the shape of Cu ions, like why can't you say that it competes with the substrate and it becomes a competitive inhibitor?

Because it's sort of a fact that metal ions do not attach themselves to the active site of the enzyme. Hence, they are not 'competing' with the substrates. They are simply changing the shape of the enzyme. This will explain better.

Specimen paper 2001, Q3 a iii) - What's the answer?

I'm not sure about this question. Maybe, because protease works at a range of pH and it is difficult or inaccurate to deduce the range for the graph.

Specimen paper 2001, Q4 is about genetic engineering, is that part of our syllabus?

Yes, it's included. It'll be easy to solve this question, once you learn the concept.

Specimen paper 2001, Q3 b) - What's the answer?

Optimum temperature for the enzyme protease to work upon.

[Amelia]

Explain why sickle cell anaemia is common in areas where malaria is endemic ?
0/n 6b p2
 

Sickle-cell anaemia provides protection against malaria. The parasite cannot survive in the blood cells of a person who has got the heterogenous sickle cell genes.

Individuals carrying just one copy of the sickle mutation (inherited from either the father or mother) were known not to develop sickle cell anemia, leading rather normal lives. However, it was found that these same individuals, said to carry the sickle cell trait, were in fact highly protected against malaria, thus explaining the high prevalence of this mutation in geographical areas where malaria is endemic.

[**RoRo**]

Because it's sort of a fact that metal ions do not attach themselves to the active site of the enzyme. Hence, they are not 'competing' with the substrates. They are simply changing the shape of the enzyme. This will explain better.

I'm not sure about this question. Maybe, because protease works at a range of pH and it is difficult or inaccurate to deduce the range for the graph.

Yes, it's included. It'll be easy to solve this question, once you learn the concept.


Optimum temperature for the enzyme protease to work upon.

THANK YOU!

[Aadeez || Zafar]

Sickle-cell anaemia provides protection against malaria. The parasite cannot survive in the blood cells of a person who has got the heterogenous sickle cell genes.

Individuals carrying just one copy of the sickle mutation (inherited from either the father or mother) were known not to develop sickle cell anemia, leading rather normal lives. However, it was found that these same individuals, said to carry the sickle cell trait, were in fact highly protected against malaria, thus explaining the high prevalence of this mutation in geographical areas where malaria is endemic.

malarial parasite cnt acctually enter the RBC which r not biconcav

it cn attack  only healthy RBC

SICKLE CEELL ANEMIA cuses deformation of RBC and it is HEREDITRCAL desease cused by Genetic DISOORDER

[Vampire-Love4ever]

Explain how crossing over leads to variation.

[Master_Key]

Explain how crossing over leads to variation.

Crossing over changes some of the chromatids sequence. This results in different alleles expressed. So variation is seen.

[Vampire-Love4ever]

Crossing over changes some of the chromatids sequence. This results in different alleles expressed. So variation is seen.

Thanks.

[Vampire-Love4ever]

Role of plasmodesmata.